A theater actor in his early years, Hemsley originated the role of George Jefferson on All in the Family in 1973. Less than two years later, George and Louise Jefferson (Isabel Sanford) moved on up with their own spin-off The Jeffersons, which followed the family's exploits in running a dry-cleaning business. The Jeffersons were one of the first affluent African-American families depicted on television. After the show's cancellation in 1985, Hemsley reunited with the original Jeffersons cast members for a brief Broadway adaptation of the show.

Hemsley's other credits include NBC's Amen, The Fresh Prince of Bel-Airand Dinosaurs. His most recent work was a guest spot on a 2011 episode Tyler Perry's House of Payne, on which he reprised his role as George Jefferson.